Development of Processing Maps for DC Cast Modified and Unmodified Hypereutectic Al-Si Alloys

2011 ◽  
Vol 213 ◽  
pp. 116-120
Author(s):  
Ke Zhun He ◽  
Fu Xiao Yu ◽  
Da Zhi Zhao ◽  
Liang Zuo
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Strain ◽  
Strain Rate Range ◽  
Instability Region ◽  
Processing Maps ◽  
Unmodified Alloy ◽  
Primary Si

The hot deformation behavior of DC cast phosphorous modified and unmodified hypereutectic Al-Si alloys was studied in the temperature range of 400-500 °C and strain rate range of 0.001-1 s-1. Processing maps were developed to evaluate the efficiency of the hot deformation and to identify the instability region. The results show that the peak stresses of the unmodified alloy are higher than that of the modified alloy at the strain rate of 1 s-1 and temperatures of 400 and 440 °C. The maximum power dissipation efficiencies for both the alloys are in the region of T=480-500 °C and =0.01-0.1 s-1. The flow instabilities for both the alloys occur in regions of high strain rate about 1 s-1 and temperature about 400 and 500 °C. The instability region area of the unmodified alloy is larger than that of the modified alloy. In addition, the primary Si cracking frequencies of the unmodified alloy are higher than that of the modified alloy when compared at the same deformation rate and temperature. The coarser primary Si particles of the unmodified alloy cause higher stress concentration around them when deformed at low temperature and high strain rate.

Characterization of Hot Deformation of Nb-V-Ti Microalloyed Steel Using Processing Map

2009 ◽  
Vol 79-82 ◽  
pp. 1439-1442
Author(s):  
Song Xiang ◽  
Guo Quan Liu
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Microalloyed Steel ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Peak Efficiency ◽  
Power Dissipation Efficiency ◽  
Working Parameters

The hot deformation behavior of Nb-V-Ti microalloyed steel in the temperature range of 850°C～1100°C and the strain rate range of 0.001s-1～30s-1 was investigated by establishing the processing maps. The strain rate sensitivity (m), power dissipation efficiency (η) and instability parameter were calculated based on the experimental compression data and are plotted in the temperature–strain rate plane to obtain power dissipation and instability maps. The processing maps exhibit that the deformation at 1000°C and 2s-1 is one peak efficiency of power dissipation of 21%, the deformation at 1050°C and 0.01~0.001 s-1 is another peak efficiency of power dissipation of 45%. The optical microstructure observations show that they represent two dynamic recrystallization domains. Based on the above processing maps, the hot working parameters were optimized.

scholarly journals Deformation Resistance and Recrystallization of Commercially Pure Titanium in the High Strain Rate Hot Deformation

1986 ◽  
Vol 72 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Takehide SENUMA ◽  
Hiroshi YADA ◽  
Hirobumi YOSHIMURA ◽  
Hisaaki HARADA ◽  
Takuji SHINDO ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strain ◽  
Pure Titanium ◽  
Deformation Resistance ◽  
Commercially Pure Titanium ◽  
Commercially Pure

scholarly journals Study on Plastic Deformation Behavior of Mo-10Ta under Ultra-High Strain Rate

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1153
Author(s):  
Ping Song ◽  
Wen-Bin Li ◽  
Yu Zheng ◽  
Jiu-Peng Song ◽  
Xiang-Cao Jiang ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Behavior ◽  
High Strain ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Rate Range ◽  
Strain Relationship

This study investigated the deformation behavior of the Mo-10Ta alloy with a strain rate range of 102–105 s−1. The Split Hopkinson pressure bar (SHPB) experiments were conducted to investigate the influence of deformation conditions on the stress-strain relationship and strain rate sensitivity of the material within a strain rate range of 0.001–4500 s−1. The Shaped Charge Jet (SCJ) forming experiments under detonation loading was conducted to clarify the dynamic response and microstructure evolution of the material within an ultra-high strain rates range of 104–105 s−1. Based on the stress-strain relationship of Mo-10Ta alloy at high temperature (286–873 K) and high strain rate (460–4500 s−1), the influence of temperature and strain rate on the activation energy Q was analyzed. The results indicate that the material strain rate sensitivity increased with the increase in strain rate and strain. Meanwhile, the activation energy Q decreased as the temperature and strain rate increased. The plasticity of the Mo-10Ta alloy under the condition of SCJ forming was substantially enhanced compared with that under quasi-static deformation. The material grain was also refined under ultra-high strain rate, as reflected by the reduction in grain size from 232 μm to less than 10 μm.

scholarly journals High Strain Rate Superplasticity in Al-Zn-Mg-Based Alloy: Microstructural Design, Deformation Behavior, and Modeling

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2098 ◽  
Author(s):  
Olga Yakovtseva ◽  
Maria Sitkina ◽  
Ahmed O. Mosleh ◽  
Anastasia Mikhaylovskaya
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
High Strain ◽  
Flow Behavior ◽  
Constant Strain Rate ◽  
Superplastic Forming ◽  
High Strength ◽  
Strain Rate Range ◽  
Strain Rates

Increasing the strain rate at superplastic forming is a challenging technical and economic task of aluminum forming manufacturing. New aluminum sheets exhibiting high strain rate superplasticity at strain rates above 0.01 s−1 are required. This study describes the microstructure and the superplasticity properties of a new high-strength Al-Zn-Mg-based alloy processed by a simple thermomechanical treatment including hot and cold rolling. The new alloy contains Ni to form Al3Ni coarse particles and minor additions of Zr (0.19 wt.%) and Sc (0.06 wt.%) to form nanoprecipitates of the L12-Al3 (Sc,Zr) phase. The design of chemical and phase compositions of the alloy provides superplasticity with an elongation of 600–800% in a strain rate range of 0.01 to 0.6/s and residual cavitation less than 2%. A mean elongation-to-failure of 400% is observed at an extremely high constant strain rate of 1 s−1. The strain-induced evolution of the grain and dislocation structures as well as the L12 precipitates at superplastic deformation is studied. The dynamic recrystallization at superplastic deformation is confirmed. The superplastic flow behavior of the proposed alloy is modeled via a mathematical Arrhenius-type constitutive model and an artificial neural network model. Both models exhibit good predictability at low and high strain rates of superplastic deformation.

Hot Deformation Resistance of an AA5083 Alloy under High Strain Rate

2014 ◽  
Vol 626 ◽  
pp. 553-560
Author(s):  
Shi Rong Chen ◽  
Chung Yung Wu ◽  
Yi Liang Ou ◽  
Yen Liang Yeh
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strain ◽  
Load Cell ◽  
Deformation Resistance ◽  
Strain Rates ◽  
Flow Curves ◽  
Aa5083 Alloy ◽  
Temperature Strain

Axisymmetric compression tests using Gleeble 3800 simulator were carried out to investigate hot deformation behaviors of an AA5083 alloy under high strain rate conditions. Sharp temperature rise and load cell ringing characterized by severely vibrational load responses were encountered at strain rates higher than 20 s-1 and sample buckling occurred at low temperatures. The load cell ringing was corrected using a moving average method with a two-way filtering operation to correct phase distortion. Isothermal flow curves were obtained by fitting the instantaneous temperatures into a binomial function, while buckling was correlated with sample height and Young’s modulus. After the corrections, hyperbolic sine equation was successfully used to extend from the hot tensile data having strain rates lower than 3 s-1 to 100 s-1. Quantitative analyses were accordingly made over the effects of temperature, strain rate and work hardening behavior on the flow curves. The previous constitutive equation in form of temperature, strain and strain rate was modified to predict the hot deformation resistance of the AA5083 alloy at temperatures of 250-450oC under the high strain rate operations.

Hot Deformation Behavior and Microstructure Evolution of a DC Cast Hypereutectic Al-Si Alloy

2012 ◽  
Vol 151 ◽  
pp. 332-336
Author(s):  
Ke Zhun He ◽  
Fu Xiao Yu ◽  
Da Zhi Zhao ◽  
Liang Zuo
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Peak Stress ◽  
Strain Rate Range ◽  
Hot Deformation Behavior ◽  
Strong Function ◽  
Primary Si

The hot deformation behavior and microstructure evolution of a DC cast hypereutectic Al-Si alloy was studied in the temperature range of 400-500 °C and strain rate range of 0.001-1 s-1. The results show that the as-cast microstructure of the alloy consists of polygonal primary Si particles and α-aluminum dendritic halos with Al-Si eutectics and intermetallic compounds segregated into the interdendritic regions. The flow stress of the alloy is a strong function of temperature and strain rate, and the peak stress is increased with the decrease of deformation temperature and the increase of strain rate. All the true stress-true stain curves in the experiments exhibit dynamic softening. The fracture frequency of primary Si particle is decreased with the increase of deformation temperature and the decrease of strain rate. The dynamic flow softening is mainly as a result of dynamic recrystallization.

Characterization of Hot Deformation Behavior of Zr-4 Alloy in Material Application Area

2012 ◽  
Vol 578 ◽  
pp. 202-205
Author(s):  
Guo Qing Lin
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Peak Efficiency ◽  
Hot Deformation Behavior ◽  
Rate Range ◽  
Temperature Range

The hot deformation behavior of Zr-4 alloy was studied in the temperature range 650-900°C and strain rate range 0.005-50s-1 using processing maps. The processing maps revealed three domains: the first occurs in the temperature range 780-820°C and strain rate range 0.005-0.05s-1, and has a peak efficiency of 45% at 790°C and 0.005s-1; the mechanism is the dynamic recrystallization. The second occurs in the temperature range greater than 900°C and strain rate range 0.05-0.8s-1, and has a peak efficiency of 40% at 900°C and 0.5s-1, which are the domains of dynamic recovery. In addition, the instability zones of flow behavior can also be recognized by the maps in the temperature range 650-780°C and strain rate range 0.01-0.1s-1, which should be strictly avoided in the processing of the material. Zr-4 alloy is the material for pressure tube applications in nuclear reactors and has better strength and a lower rate of hydrogen uptake compared to other materials under similar service conditions.

scholarly journals Influence of Hot Deformation and Precipitates on the Recrystallization of Nb-V-Ti Free-Cutting Steel

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1587
Author(s):  
Yang Yang ◽  
Xian-Ming Zhao ◽  
Chun-Yu Dong ◽  
Xiao-Yu Zhao
Keyword(s):  
Grain Boundary ◽  
High Strain Rate ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strain ◽  
Boundary Migration ◽  
Great Influence ◽  
Material Model ◽  
Dislocation Motion ◽  
Cutting Steel

Nb, V, and Ti were added to free-cutting steel to improve its mechanical properties by means of precipitation strengthening and fine grain strengthening. The process parameters during the hot deformation of Nb-V-Ti free-cutting steel were studied at strain rates of 0.01–10 s−1 and temperatures of 850–1250 °C. The isothermal compression test results showed that the temperature rise at low deformation temperature and high strain rate has a great influence on the softening of the steel. The processing maps at strains of 0.3–0.6 were established based on a dynamic material model (DMM). When the strain was 0.6, the optimum hot-working window was at a temperature in the range of 1150–1250 °C and at a strain rate in the range of 0.01–0.1 s−1. The instable regions were mainly located at low temperature and high strain rate. The instable characteristics included the mixed grains around the MnS phase, flow localization, and intense deformation. In general, the existence of MnS leads to a decrease in the toughness of the steel. The MnS phase was easy to be broken when the compression tested at a lower temperature, e.g., 850 °C and at a higher strain rate, e.g., 10 s−1; its morphology changed from a long-rod shape to a discontinuous shape, and then, to a dot-like shape with the decrease in temperature from 1250 to 850 °C and the increase in strain rate from 0.01 to 10 s−1. The nucleation mechanism of this steel was grain boundary bulging. The size of fine (Nb,Ti) (C,N) precipitates is less than 10 nm, inhibiting austenite recrystallization and leading to austenite strengthening during hot deformation at 850 °C. Moreover, the dislocation motion and grain boundary migration were greatly inhibited by the Ti-rich(C,N) and MnS throughout the entire hot deformation process.

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